Walking amidst “Munchkin,” “Ruby Slippers,” and “Snow Queen” at a local plant nursery, I wondered if I had wandered into some magical land “over the rainbow.” I was in the section of the nursery dedicated to hydrangeas!
Hydrangeas include more than 75 species of evergreen or deciduous shrubs native from Asia to North America. They are widely grown, relatively pest free, and require minimal annual maintenance. Consider including them in your landscape design—they will bring you multi-season enjoyment.
Hydrangeas in North Carolina
The most common species of hydrangeas found in North Carolina landscapes are:
- Bigleaf hydrangeas (Hydrangea macrophylla) come in two flower types: lacecap and mophead. If you adjust soil pH, you can modify their bloom color. They will bloom blue in acid (below 6) pH soil and pink in high (above 7) pH soil. This is a function of aluminum availability. White bigleaf hydrangeas will not change color with soil pH. There are over 1,000 cultivars of this species—some recent introductions may re-bloom on new wood. In Western North Carolina most bloom from June to August.
- Mountain hydrangeas (Hydrangea serrata) also come in both lacecap and mophead flower types. They grow 2 to 5 feet high and 4 to 6 feet wide. There are over 100 cultivars. They are native to Asia, not our mountains, and bloom in May.
- Oakleaf hydrangeas (Hydrangea quercifolia) grow 4 to 8 feet high and wide and are one of the hydrangeas native to the southeastern states. They flower in June with blooms lasting three to four weeks. Leave the spent bloom heads on the plants to add winter interest to the garden.
- Smooth hydrangeas (Hydrangea arborescens) are native to our area and grow 3 to 5 feet high and wide. Flowers appear in June and last 3 to 4 weeks.
- Peegee hydrangeas (Hydrangea paniculata) grow 15 to 25 feet high and 10 to 20 feet wide, if left unpruned. Their flowers open white from June through August.
- Climbing hydrangeas (Hydrangea anomala subsp. petiolaris) are vines that can grow 60 to 80 feet tall if left untrimmed. Asian natives, they are slow to establish, but you will enjoy their ability to climb just about any vertical surface. Bloom time is late June to early July.
- Hydrangea macrophylla, H. serrata, and H. quercifolia bloom on old (last year’s) wood—prune after flowering. You can trim to shape them to fit into your landscape design. Remove dead, diseased, and damaged limbs at any time.
- Hydrangea arborescens and H. paniculata bloom on new wood—prune in late winter (February to early March). They benefit from being cut back to six inches off the ground (i.e., rejuvenation pruning). Promptly remove all old, dead, diseased, and damaged stems.
- Hydrangea anomala subsp. petiolaris requires very little pruning—train to grow this climbing hydrangea on its support surface.
Article written by Bob Wardwell, Extension Master GardenerSM Volunteer.
It’s All in the Soil! The Chemistry Behind Hydrangea Colors
YouTube video from the American Scientist
Prune hydrangeas at the wrong time and you snip off the season’s blooms.
by Glenn Palmer, Buncombe County Extension Master GardenerSM Volunteer
Smooth and Oakleaf Hydrangeas
by Ervin Evans and Richard E. Bir
Horticultural Science, NC State Extension